The present invention relates to a gaseous discharge display.
There have been some conventional gaseous discharge display devices of direct current type having an auxiliary discharge mechanism. FIG. 7 is the one having no resistance connected to each display cell, while FIG. 8 is the one having resistances connected to corresponding display cells in series.
In FIGS. 7 and 8, a reference numeral 10 represents a front plate, a reference numeral 12 represents a rear plate. The front plate 10 is provided with a black matrix 14. The rear plate 12 is provided with a white back 16 of an isolating layer, and a phosphor 18. A partition wall or barrier 20 separates a space between the front plate 10 and the rear plate 12 into numerous cells. Furthermore, in the drawings, a reference numeral 22 represents a display anode bus bar, a reference numeral 24 represents a display anode, a reference numeral 26 represents an auxiliary anode bus bar, a reference numeral 28 represents an auxiliary anode, a reference numeral 30 represents a cathode bus bar, a reference numeral 31 represents a display cathode, and a reference numeral 32 represents an auxiliary cathode. The display anode 24 and the display cathode 31 cooperatively constitute a display cell 34. The auxiliary anode 28 and the auxiliary cathode 32 cooperatively constitute an auxiliary cell 36. The partition wall 20 is provided with a priming slit 38 which guides an exited particles generated by the auxiliary cell 36 to the display cell 34.
In FIG. 8, a reference numeral 40 represents a display electrode resistance provided on a corresponding display electrode 24. The resistance equipped, gaseous discharge display shown in FIG. 8 realizes the pulse memory driving of the display cell 34 using a constant-voltage source. If the gas pressure is increased to elongate the life of the gaseous discharge display, the V-I characteristics of a cell of the gaseous discharge display will be flattened. Thus, the writing operation is impossible when the display electrode resistance 40 is omitted.
The auxiliary cell 36 acts to quickly build up the writing discharge in a display cell 34 within a short time of approximately 1 .mu.s. The auxiliary cell 36 causes a discharge occurring simultaneously with the writing pulse. FIG. 9 is a view showing a fundamental arrangement of the resistance equipped, gaseous discharge display shown in FIG. 8. This resistance-equipped gaseous discharge display is applied pulses having waveforms shown in FIG. 10 according to the pulse memory driving method. In FIG. 9, a reference numeral 43 represents a memory panel of this resistance-equipped gaseous discharge display. In the waveforms shown in FIG. 10, a sustaining pulse has a period T of 4 .mu.s and a width .tau..sub.sp of 1 .mu.s; a writing pulse has a width .tau..sub.w of 2 82 s; and a cathode scan pulse has a width .tau..sub.k of 2-3 .mu.s. In such a resistance-equipped gaseous discharge display, the auxiliary cell 36 is usually driven by a constant-current source. An auxiliary anode bus bar resistance 42 shown in FIG. 9 can act as such a constant-current source.
In the arrangement of FIG. 8, one auxiliary cell 36 is provided for each of two display cells 34, 34. On the other hand, the arrangement of FIG. 9 is different from the that of FIG. 8 in that one auxiliary cell 36 corresponds to only one display cell 34, although the operational function is essentially the same.
As explained previously, the auxiliary cell 36 is driven by a constant-current source in the resistance-equipped gaseous discharge display. For a large scale gaseous discharge display, the electrostatic capacitance between the auxiliary anode 28 and the cathode 32 becomes fairly large. For example, the capacitance of a display having a height of 600 mm will be in a level of approximately of 60 pF. The auxiliary cell 36 is generally equipped with no barrier to be provided between cells; therefore, a small voltage difference of 5-10 V will be caused between the discharge ignition voltage and the maintaining voltage corresponding to a large discharge current.
In a discharge of the next line, it is necessary to increase the discharge ignition voltage by an amount equal to the above voltage difference. In this case, current I is defined by I=C.multidot..DELTA.V/.DELTA.t. In the case of C=60 pF, .DELTA.V=10 V and .DELTA.t=2 .mu.s, the current I is obtained as I=300 .mu.A. When the auxiliary cell 36 is discharged, electric charges flow also from this capacitance C. Accordingly, an approximately twice large discharge current of 600 .mu.A flows through the auxiliary cell 36.
For this reason, the above-described conventional gaseous discharge display is encountered with the following problems:
(1) Large spattering occurs in the auxiliary cell due to a large discharge current flowing through the auxiliary cell; thus, operation of the auxiliary cell is unstabilized and the life of the auxiliary cell is shortened.
(2) Electric power consumption of the auxiliary cell is increased; thus, an overall efficiency of the gaseous discharge display is reduced.
(3) A large current flows through a driving circuit of the auxiliary cell, such as a cathode driving circuit; accordingly, a large power driving IC is required.
(4) A high pressure value obtainable for the gas filled in the cell is limited; hence, the life of the gaseous discharge display obtained will be unsatisfactory. And,
(5) An amount of the priming discharge is so increased that the erroneous discharge may be induced in the non-writing cell. Therefore, it is necessarily required to precisely design the size of the priming slit which guides the priming discharge.
Furthermore, there is the possibility of unstabilizing the operation of the auxiliary cell in the case of the memory driving of display cell. This is because the auxiliary anode constituting the auxiliary cell is subjected to the sustaining pulse for the memory driving of the display cell which is added through a stray capacitance.